Process for softening water



july 22, 1924n l 1,502,188

F. E. HARTMAN ET AL PRoEss Foa soFTNING WMER Filed Marh 2l, 1922 Patented duly 22, i924.

iraiig FRANK E. HARTMAN AND HARRY BURTON HAETMAN, OF SCDTTDALE, PENNSYL- 'VANIA, ASSGNORS TO ELECTRIC WATER STERILIZER in GZGNE COMPANY, OFl

SCOTTDALE, PENNSYLVANIA, A CORPORATEON Oli' EENNSYLVANA.

PROCESS FOR SOFTENING- VATEB.

Application :filed March 21, 1922. Serial No. 545,508.

To all Iwhom t may concern.'

Be it known that we, FRANK and HARRY B. HARTMAN, citizens of the United. States, residing at Scottdale, in the in View the acceleration of the softening' process by assisting chemical reaction through the action of anelectrolytic cell, that is, by electrolysis, which, if not actually increasing the ionization atleast accelerates the reaction between the ions and by the speed of reaction thus obtained rapidly carries the process to completion withoutv the addition oi appreciable excesses of precipitating reagent which frequently results in rendering the water alkaline. f Accordingly, it will be apparent that the process contemplated by the present invention generally involves the use of an electrolytic cell to obtain the benefits of highly ionized solutions thus to obviate the necessit of resorting to the usual practice of 'uti izing an 'excess amount of precipitating reagent to efect the completion or" the reaction.

Primarily therefore the invention has in view to obtain a highly ionized solution, or in other words, proposes to predispose the water to rapid reaction by the influence of electrolysis and to that end combines with the chemical process an electrolytic step which may be performed at any suitable or convenient point in the rocess according to the character of the c emical reactions in- .volved ln all cases however, the electrolysis is accomplished at-the most advanta.

geous point to eect maximum ionization.

Obviousl the process may be practiced by any suitab e and/convenient type of apparatus, but forI urpose of illustration, the accompanying rawings show more or less diagrammatically the general organization et instrumentalities involved. ln the draw in s:

lfigure is a plan view ci an improved plant for carrying out our novel process.

Fig. 2. is a side elevation thereof, and

E. HARTMAN Fig. 3 is a diagrammatic view, in section, of the electrolytic cell used in the process.

Similar 'reference characters designate corresponding parts throughout the several figures of the drawings.

It is a well known fact that natural waters are hard or soft according to their origin and the chemical character of the soils with which they contact and in thecase ofl the sovcalled hard waters it is desirable as well as necessary to 'subject the same to so-called softening processes for `rendering them better adapted to home as well as industrial use. the presence of the bi-carbonates of calcium and magnesium together with the chlorides, sulpliates and nitrates of the same basis and the hardness is usually of two kinda-temporary and permanent. The bicarbonates constitute what is known as the temporary hardness while the chloride, sulphate and nitrate constitute the permanent hardness.

rlemporaryy hardness may be dispelled by boiling or by the use of suitable quantities The so-called hard, waters are due to of lime, while the permanent hardness caused by the salts of calcium and magnesium is usually removed by the use of 'soda ash or NaZCO3 as the reagent. lt will therefore be apparent that the softening of water depends upon chemical reactions between the reagents and the oending-salts contained in the water.

ln 'inorganic chemistry all reactions can be said to be tiinolecular, that is, a third substance is necessary to facilitate the reaction between the two other substances. This third substance is in inost cases either an aqueous vapor or water which accelerates the velocity of chemical reactions by actin as an electrolyte. Going a step further an eniamining the electrolytic dissociation theory it is found compounds that do not respond in every respect toosniotic pressure laws, will when dissolved in water dissociate, or partly dissociate into their ions.

From observed phenomena, it appears that compounds are infinitely more active when dissolved in water and we may therefore rightly inferthat they are more active in the ionic state.

Also in the softening of water there is i another factor relating to the velocity of reaction that must be taken into constriction, namely, they law ot mass action which is ibrieiiy defined-that the amount of chemical action is proportional to the active mass l of eachy of the substances reacting, active mass being deined as molecular concentration of the reacting substances. That t say, if equivalent amounts of .two givenv chemicals are prepared for combination the reaction will proceed until a .certainA percentrage of the reacting'substances have been used' up and then the reaction `cornes" to a standstill. It will therefore be v.seen .that

an excess amount of precipitating agent.

. must be employed to complete'the precipita- 4tion of the substance in solution, and 1t 1s for thisreason that an excess of the reagent.

is always used in Aanalytical chemistry.

In the softening of water however 1t 1s :desirable to avoid the use of large excess o` reagents since by so doing thev softened water 1s rendered valkaline although perhaps the hardness forming salts have been eliminated.A

Accordingly, it appears' action takes place between ionized salts, and

that the reaction proceeds according tothe mass participating. The usual way o-'aco celerating the completion of the reaction by lthe use of anl excess of precipitating agent is not desirable for the reasons heretofore given and therefore to obtain complete and edectual reaction in a water softening process the present invention proposes to utilize highly ionized. solutions. As it has'been found in practice that salts 'are much more active under the influence opelectrolysis, 1t

follows that the presence ofY electrically.

charged bodies at least accelerate reaction between the ions if not actually increasing the ionization, and `since theI presence -of' otherions does not 'retard the ionization of the reacting salts insolution it appears that the speed of reaction is greatly increased and by such speed the reaction carried to completion without necessitating the addip tion of appreciable excesses.

.l Therefore, in lcarrying forward the objects of .the present process it is -proposed *y to predispose the water into rapid reaction by, the inuence 'of electrolysis, the electro-v lytic actionv taking place either before the water enters the electrodeI chamber orafter 'it passes from the electrode chamber and before it enters the sedimentation chamber.

| The accompanying drawings illustrate a type of chemical water softening apparatus designated generallyas A Ywith which it is proposed to combine the electrode box or electrolytic cell B of the -type, for example, shown in the patentgto H. B.'Hart "man, No. 1,101,27 8, the saine being arranged posterior tothe point of chemical reagent supply according to the arrangement shown but it will ofic'ourse be understood, as heretofore pointed out that this cell may be placed anteriorto the' point 'of chemical-- that the best .rev reagentsupply in which event the chemical reagent would be supplied through the pipe line shown lin dotted lines in Figure 2.v .Inztliis connection it 'will be understood that the. introduction of the chemical reagent into the line of passage of the water with-reference tothe cell B` will largely depend upon the character of the various intermediate reactions likely to be encountered under ,diiiierent circumstances. In all cases however, the *function* ofthe electrof .into intermediate reaction andat the same time produce a coagulant.

A Referring more in detail to the dralwings, 5 represents the influent pipe which conveys the water to the purifying plant. Located at intervals' along this pipe are jet mixers '6 and 7 by means of whlch reagents such for example as used iny the' well .known Porter-Clark pr ,ess may be mixed with the raw v.watenglhese chemicalsl are troduced by pipes 8 and 9 which are re spectively provided'with controllin valves ,8&2 and Q. The jet is 'employed or prev'venting back pressure .in either oriboth of the pipes 8 and'9, as such aback pressure might prevent or retard the proper low of the solutions. n.-

The water thus treated, passes through a valve l() and thencethrough an inlet pipeV 11 tothe electrolytic cell B; This cell or unit comprises top and bottom plates 13 and 14 which are heldv together by bolts 15. A pluralityhof electrode plates 16 of 'iron or Vother suitable material and of bipolar construction are disposedbetween said plates 13 and 14, The'electrodeplates are separated by spacing gaskets 17 having openingsy 18 for-the upward passage of the water, and openings 19 for the downward passage of the water after it has passed all of these electrodes in atortuous path, said water proceeding throughthed1scharge pipe 2O and control valve 21 thereof. The water then passes into a VAstand pipe 22 of a' sedimentation tank 23 which has a suiiicient lytic cell will be to predispose the water' surface to permit the deposition of precipitates during the iow of the water through it towards the outlet or overiiow pipe 24. In order to prevent the direct passage of water from the stand pipe 22 to the overflow.

4pipe 24, a partition or battle 25 is employed in said tank. The water passes from the 'overflow pipe 24 through a pipe 26, having controlling .both filters 28-28. Thus by controlling the valves 27-27, to either one or lil) either or both of said pipes 6 and 7 vmay be connected with the influent pipe 5 at the point ir between the electrolytic cell. B and the sedimentation tank 23, as shown by the dotted lines in Fig. 2.

rlhe water in passing through the cell- 'B is subjected to an intense electrolyzing current, and electrolysis ofthe salts occurs. Some acid ions liberated at the anode attack the latter, if'made of aluminum or iron, and from corresponding salts which are dislodged and enter the body of the water. The basic ions liberated -forin hydroxides and likewise pass into the water. Vhen these two electrolytes blend they combine to form iron or aluminum hydroxides andf re-establish the normal condition found. before electrolysis. This hydroxide however serves as a coagulant for the water and causes more rapid'sedimentation, not only of the precipitated and suspended calcium and magnesium salts, but of other suspended matter as may have been' present'in the raw water. The tortu'ous passage through the mixing chamber further serves as a mining device for effecting diffusion and thorough intermingling of the reagents yand the water without a special chamber for the purpose.

le have found however that with such a cell it is possible for polarization to occur i. e. in electrolyzing the salts, hydrogen and oxygen from the water arel separated on the surface of the electrodes, thus diminishi ing their area and furthermore forming hydrogen4 and oxygen electrodes'with a re- .sultant E. M. F. which interferes with the operation of the cell.

To avoid this undesirable feature, we place the water under sufficient pressure to attain a velocity sufficient to sweep the electrodes clear of such globules as they form. Good results are obtained with a velocity of one and one-half feet per second.

The water thus treated passes into the reaction and sedimentation tank or basin 23 in which the suspended and precipitated matters are deposited. v

From the foregoing it is thought that the features and advantages of the present improvement will be readily understood by those skilled in the art and it will of course be understood that any suitable and convenient type of apparatus may be used to carry the invention into effect.

We claim z- A process 4for aiding the chemical .softening of water, -whicli consists in injecting a softeningreagent under pressure into the feed line, next predisposing the water under pressure to rapid reaction by electrolysis, A

and subsequently conducting the chemically and'electrically' treated water throughA a relatively capacious sedimentation basin.

In testimony whereof we hereunto ailix our signatures in the presence of -two Witnesses.

FRANK E. HARTMAN.

HARRY BUXTON HARTMAN. Witnesses:

E. L. KING, MABEL FREEMAN 

